Recently, owing to significant advance in semiconductor techniques, performance and operation speed of electronic equipment apparatuses such as LSI (Large Scale Integration) have been improved. Therefore, costs required for designing and verifying a power supply of each electronic equipment apparatus have also increased.
In order to reduce the power-supply design cost for electronic equipment apparatuses, verification performing a simulation for electronic equipment apparatuses has been actively pursued at the phase of design. It is possible to evaluate a superior or inferior power-supply design for electronic equipment apparatuses by analyzing such verification using the simulation, thereby solving a problem in that power-supply redesigning must be performed after making a preproduction sample of an electronic equipment apparatus. Accordingly, it is possible to reduce the power-supply design cost for the electronic equipment apparatus.
In addition, various kinds of technique for supporting the power-supply design for electronic equipment apparatuses by employing simulation have been disclosed.
In an example of the disclosure, in order to cancel a multipath phasing phenomenon in which multiple waves through different transmission paths interfere with each other that degrades received waves, an impedance of the power supply is computed in advance by simulation, so as to determine the presence or absence of resonance in the power supply and support the design thereof (see, for example, Patent-Document 1).
In another example of the disclosure, design support is performed by adjusting the model of simulation due to the measurement of a power-supply circuit of an electronic equipment apparatus (see, for example, Patent-Document 2).
In another example of the disclosure, appropriate design supporting is performed by producing an analysis model by using lots of design information items for an electronic equipment apparatus, and determining decoupling capacitance which is required for arranging capacitors in a power-supply circuit and is one of the important elements for the power-supply design (see, for example, Patent-Document 3).
Additionally, it is very important in the power-supply design of an electronic equipment apparatus to suppress variation in the voltage of the relevant power supply.
More specifically, when a working part of the electronic equipment apparatus operates in various ways, electric current flows from the power supply. Here, the working part of the electronic equipment apparatus consists of many electronic components such as an LSI, and each circuit of the electronic equipment apparatus is activated or inactivated according to the working state of each electronic component, so that the current which flows through the working part varies according to the number of circuits that work at different values of timing. Such a current variation causes a variation in the voltage of the power supply. In consideration thereof, optimum power-supply design is performed in which the variation in the voltage of the power supply is analyzed so as to supply a stable power-supply voltage.